Holley Model 4150 Aluminium Double Pumper Carburettors Offer An Improved Fuel Design And Efficient Construction Features For Huge 38 Percent Weight Savings Over Standard Carbs. Optimized For Street And Strip Calibration. They Provide Great Performance Right Out Of The Box. Holley Carburettors Include Dual Accelerator Pumps - Mechanical Secondaries And Dual-Feed Inlets For Constant High-Volume Fuel Delivery. Plus Power-Valve Blowout Protection And A 100 Percent Wet-Flow Test These Units Set A Standard For Performance And Reliability That''S Hard To Beat.